Hudson Brown travels to the Beaumont Proton Therapy Center in a Dodge Challenger, right, painted like a Bumblebee Transformer, followed by 25 Camaros driven by members of the Motor City Camaro Club and Eastern Michigan Camaro Club. The Bumblebee Transformer was originally a Chevy Camaro. Todd McInturf, The Detroit News

Hudson Brown, with his mother, Megan Brown, 36, both of Grosse Pointe Farms, smacks the hand of Marcquise Copeland, left, 36, of Livonia, who portrays the Bumblebee Transformer. He is the owner of Copeland Entertainment and owns 45 character costumes. Todd McInturf, The Detroit News

Hudson Brown gets a kiss from his maternal grandmother, Sylvia Ross-Schultz, 65, of St. Clair Shores, with Marcquise Copeland, 36, of Livonia, portraying the Bumblebee Transformer. He is the owner of Copeland Entertainment and owns 45 character costumes. Todd McInturf, The Detroit News

Hudson Brown looks up at Marcquise Copeland, 36, of Livonia, who portrays the Bumblebee Transformer. He is the owner of Copeland Entertainment and owns 45 character costumes. Todd McInturf, The Detroit News

Actor Mark Wahlberg gives a brief recorded video message to Hudson Brown before the group eats Wahlburgers in the Proton Therapy Center lobby. Wahlberg portrays, Cade Yeager, in a few Transformers movies. Todd McInturf, The Detroit News

Andrew Carpenter, 6, of Birmingham, a friend of Hudson Brown, plays with his Bumblebee Transformer as he and others wait for Brown's arrival to the Beaumont Proton Therapy Center in Royal Oak, Friday, April 13, 2018. Brown, who was diagnosed with medulloblastoma, a large brain tumor, celebrates his last of 30 proton-beam radiation treatments by ringing the "end-of-treatment" bell before a party in the lobby of the treatment center. Todd McInturf, The Detroit News

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Hudson Brown, 5, holds onto 'Maddie,' a hospital therapy dog, as he walks with his family to ring the 'end-of-treatment' bell at the Beaumont Proton Therapy Center in Royal Oak. Brown, who was diagnosed with medulloblastoma, a large brain tumor, celebrates his last of 30 proton-beam radiation treatments by ringing the ‘end-of-treatment’ bell before a party in the lobby of the treatment center, Friday morning, April 13, 2018.(Photo: Todd McInturf / The Detroit News)Buy Photo

His parents rushed him to a nearby emergency room. The diagnosis was devastating: brain cancer. Specifically, medulloblastoma.

A large tumor had developed in the back of his brain and on top of his brain stem. Medulloblastoma is a long word with too many syllables to be attached to a five-year-old boy from Grosse Pointe Farms.

“One day, my five-year-old is going to pre-K, and the next day his whole world is turned upside down,” said his mom, Megan Brown, 36.

Before Hudson’s diagnosis, his headaches could be managed by over-the-counter medicines. But their intensity grew, prompting an MRI and a CT scan at St. John Hospital & Medical Center’s emergency room on Moross in Detroit revealed the cancer.

Hudson underwent surgery that removed 90 percent of the tumor at St. John, and his mom said the doctors they consulted suggested radiation therapy at Beaumont’s new Proton Therapy Center in Royal Oak, which opened in June, to be the next step of his treatment. It is one of only 28 in the country and the only operational facility of its kind in Michigan.

“We felt so blessed that the center is only 30 miles from our house,” Megan said.

Dr. Peter Chen, Hudson’s radiation oncologist at the Proton Therapy Center, said the tumor caused Hudson to have typical symptoms, including unsteady gait, headache and vomiting.

“As well, he had confusion, not being able to recognize his parents,” Chen said.

Over a six-week period — five days a week — Hudson received 30 treatments.

Proton beam therapy — a radiation method that uses protons to treat the cancer — was the best decision for Hudson, according to Dr. Peyman Kabolizadeh, clinical director of Beaumont’s Proton Therapy Center, who said, “You can think of proton as more of a targeted treatment.”

“It resulted in decreasing the dose to adjacent critical organs, which are in developing growing phase in this patient,” he said.

Friday marked the last day of proton beam therapy. To celebrate, he was treated to a surprise “Transformers” party. Hudson is a huge “Transformers” fan, and he particularly loves the Bumblebee character.

So he arrived at the center with great fanfare. A state police squad car with flashing lights led the way. It was followed by Hudson riding in a yellow Bumblebee-styled Challenger with the Transformer joining him, followed by a caravan of more than 20 Camaros from local clubs.

When the Challenger pulled up in front of the Proton Center, the Transformer exited and opened the back door for Hudson and his mom. Hudson hung onto his mom’s hand while staff, friends and family members cheered and applauded him.

Once inside the center, Hudson was escorted to a large golden “end of treatment” bell, where he grabbed the cord and vigorously rang it. Nurses and other staff, along with friends and family applauded, took photos and wiped away tears.

Hudson also was treated to a video message from “Transformers” movie star Mark Wahlberg, who also provided hamburgers, Hudson’s favorite food, for guests to enjoy.

“Stay strong, buddy,” Wahlberg said in the video. “You are an inspiration to everyone. God bless you. I love you, stay strong, and I look forward to meeting you soon.”

Hudson has two sisters — Cece, 2; and Emmy, 7 — and a dad, Patrick, 34, who shaved his own head to match Hudson’s.

“When his hair started falling out, I told him he could buzz cut mine,” Patrick said. “As long as his head is bald, mine will be bald, too.”

Hudson will next have chemotherapy at St. John after a four-week break.

Chen said Hudson has a “minor amount of unsteady gait, which, with physical rehabilitation, should steadily improve.”

“The proton therapy should decrease the risk of any treatment-related secondary cancer in Hudson over the next several decades,” Chen said.